The present invention relates to a method of preparing a cylindrical corrugated article by employing a sheet material.
A cylindrical corrugated article as above is usually prepared by employing a sheet material consisting of a simple substance such as paper, plastic, metal foil, etc. or a composite of such substances, and as it is necessary to stick the confronting edges of the material to each other, some heat-sealable plastic is previously applied on said confronting edges at the least.
A cylindrical corrugated article formed as above is used as, for instance, the cover a for the cup n shown in the appended FIG. 1 and 2; in the inside of this cover a, there is inserted the smooth cup base b, and the inner ridges of the corrugation of the cover a are made to adhere to the exterior of the cup base b, whereby both cylindrical articles a and b are integrated to form the cup n. The thus formed cup n has a heat resisting property due to the adiabatic effect of air inclosed in the gaps between the corrugated article a and the cup base b, and has such a merit that not only the outer wall of the cup is free from the formation of water drops thereon and is always dry to the touch but also the strength of the cup as a whole is enhanced.
On the occasion of forming a cylindrical corrugated article a as above, it has been usual to apply the method comprising cutting a flat-board type corrugated article prepared through corrugation process in advance into pieces of required size, curving said piece into a cylindrical shape, and sticking the confronting two edges to each other. However, this conventional method has been defective in that:
1. The flat-board type corrugated article is rich in elasticity and flexibility so that it is hard to cut into pieces of required size and the resulting products tend to be of irregular diameter and dimensions.
2. On the occasion of curving the flat-board type corrugated article and sticking the confronting edges of the resulting cylindrical corrugated article together, it is required to make the concave portion and the convex portion of the corrugation perfectly agree with each other, but this work is very hard to perform because of the rich elasticity as well as flexibility of said corrugated article and it is difficult to obtain a product with exactly overlapping edges.
3. Further, such a work as inserting a smooth cylindrical base in a cylindrical corrugated article formed as above has had to be performed by hand as there has not been developed any automatic apparatus apposite thereto, and therefore, the operation has been very inefficient and mass production has been infeasible.